Bonding strength between fiber and matrix is a crucial factor which can largely determine the performance of fiber reinforced geopolymer composite. However, the available information on the fiber/matrix interface properties in s lag/fly ash based geopolymer is still quite limited, which have hindered the scientific design of related fiber reinforced composites. This study presents the bonding characteristics of PVA fiber/slag-fly ash based geopolymer matrix interface determined by single fiber pullout tests. Four SiO2/Na2O ratios (0.8, 1.0, 1.2 and 1.5) within the alkaline activator were used for mixture preparation. All specimens were tested after 28-day curing. The interface characteristics including chemical bonding energy, interfacial frictional force as well as the slip-hardening properties were determined from the fiber pullout tests. It was found that the chemical bonding energy first increased and then decreased with increment of SiO2/Na2O ratio, indicating an optimal alkaline activation condition at SiO2/Na2O ratio of 1.0-1.2. On the other hand, the interfacial frictional force and slip-hardening properties seems to be not influenced by increasing the SiO2/Na2O ratio. This research provides a fundamental understanding into the interfacial bonding properties of PVA fiber to the slag-fly ash based geopolymer matrices. @en

Quantification of the CO2 binding capacity of reinforced concrete is of high importance for predicting the carbonation potential and service life of these structures. Such information is still not available for alkali activated materials that have received extensive attention as a sustainable substitute for ordinary Portland cement (OPC)-based concrete. To address this gap, this paper evaluates the CO2 binding capacity of ground powders of alkali activated fly ash (FA) and ground granulated blast furnace slag (GBFS) pastes under accelerated carbonation conditions (1 % v/v CO2, 60% RH, 20°C) for up to 180 days. The CO2 binding capacity, the gel phase changes, and the carbonate phases are investigated with complementary TG-DTG-MS, FT-IR and QXRD techniques.@en